Dieudonné, J.: Foundations of Modern Analysis, Vol. 1. Academic Press.
Hirsch, M., Pugh, C., Shub, M.: Invariant Manifolds, mimeographed. U. C. Berkeley 1974.
Irwin, M.: A Classification of Elementary Cycles. Topology9, 35–48 (1970).
Peixoto, M.: Structural Stability on Two Dimensional Manifolds. Topology1, 101–120 (1962).
Smale, S.: Differentiable Dynamical Systems. Bulletin Am. Math. Soc.73, 747–817 (1967).
Spanier, E.: Algebraic Topology. McGraw-Hill.
Winfree, A.: Patterns of Phase Compromise in Biological Cycles. Journ. of Math. Biol.1, 73–95 (1974).